The present invention relates to surgical scalpels and, more particularly, to a surgical scalpel in which an electrosurgical cutting current or an electrosurgical coagulation current can be applied to the tissue of a patient through an electrically conductive blade that is also used to effect cutting of the tissue.
Electrosurgery has become quite common for a number of reasons. Controlling bleeding during surgery is a significant problem, and it was found that coagulation, or hemostasis, could be accomplished by applying a radio frequency current to the affected patient tissue. Further, it was found that applying a radio frequency current to tissue through a scalpel facilitates the cutting action of the scalpel. Typically, an electric current is applied to the tissue of a patient via the scalpel at the same time that the scalpel is used to cut the tissue in a conventional manner. It is known that certain current wave shapes and frequencies enhance the cutting action of the electrosurgical scalpel, while other current wave shapes and frequencies tend to cause coagulation of blood in the region of an incision.
The electric current for electrosurgical procedures is provided by a generator including a radio frequency oscillator circuit. The electrosurgical current is applied to the patient by an active electrode connected to the generator by a cable, and is returned from the patient to the generator through a cable which is attached to a dispersive electrode. The dispersive electrode is secured to the patient's skin. The dispersive electrode is relatively large in area, thereby keeping the current density in the region of the dispersive electrode sufficiently low to avoid tissue burns.
Various approaches have been taken in the prior art to control the application of electrosurgical current to a patient. Commonly, a foot pedal switch has been used, with depression of the pedal resulting in either coagulation current or cutting current being supplied to the active electrode, such as shown in U.S. Pat. No. 4,640,279, issued Feb. 3, 1987, to Beard, and in U.W. patent No. 3,730,188, issued May 1, 1973, to Ellman. U.S. Pat. No. 3,601,126, issued Aug. 24, 1971, to Estes, also discloses the use of a foot pedal switch. Additionally, Estes suggests that a finger operated switch, mounted on the active electrode, may be used in lieu of a foot pedal switch.
Various single-use electrosurgical scalpels have included finger operated electrical controls. A common problem with such scalpels is reliability, since they have commonly incorporated snap switches that each consist of a snap metal dome having a peripheral edge lying on a printed circuit board land. Such a switch provides a connection to a second circuit board land when the central portion of the dome is snapped downward into contact with the second circuit board land. A problem associated with switches of this type is that the metal domes may oxidize over time, resulting in an undesired, high level of switch resistance. An additional problem is the cost associated with the manufacture of a disposable part having a great many separate components that must be carefully assembled. A further problem is that the movement of the surgeon's index finger in depressing a switch tends to cause the scalpel to pivot downward. This downward movement can be significantly amplified if the cutting blade is relatively long. Thus, switches of this sort have required care to insure that the scalpel blade is appropriately controlled.
Accordingly, it is seen that there is a need for an improved simple, reliable electrosurgical scalpel having a manually operated switch arrangement permitting the surgeon to supply electrosurgical cutting current or electrosurgical coagulation current to the electrically conductive scalpel blade.